Front derailleur for a bicycle

ABSTRACT

A front derailleur includes a fixed member, a chain guide and a linkage assembly. The fixed member has a mounting portion and a pair of mounting flanges axially spaced from each other. The linkage assembly is coupled between the chain guide and the fixed member to transversely move the chain guide. The linkage assembly includes first, second and third links. The first link is pivotally coupled to the fixed member for rotation about a first axis. The second link is pivotally coupled to the mounting flanges for rotation about a second axis. The third link is coupled to the chain guide and movably coupled to the first and second links to form a four-bar linkage together with the fixed member. The mounting flanges preferably have different axial widths. The second link preferably has a longitudinal dimension of least about 45.0 millimeters.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. patentapplication Ser. No. 09/991,880, filed on Nov. 26, 2001. The entiredisclosure of U.S. patent application Ser. No. 09/991,880 is herebyincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention generally relates to a front derailleur for a bicycle.More specifically, the present invention relates a front derailleur fora bicycle that has a fixed member with a wide support flange and a widesupport link allowing reliable movement of the chain guide.

2. Background Information

Bicycling is becoming an increasingly more popular form of recreation aswell as a means of transportation. Moreover, bicycling has become a verypopular competitive sport for both amateurs and professionals. Whetherthe bicycle is used for recreation, transportation or competition, thebicycle industry is constantly improving the various components of thebicycle. One part of the bicycle that has been extensively redesigned isthe front derailleur. A front derailleur is typically mounted onto thebicycle frame adjacent to the front sprockets.

Generally, a front derailleur includes a fixed member non-movablysecured to a bicycle frame, and a movable section supported to bemovable relative to the fixed member. Typically, the fixed member is atubular clamping member that is secured to the seat tube. Alternatively,the fixed member is sometimes coupled to the bottom bracket. In eithercase, the fixed member preferably has a curved surface designed tocontact a curved seat tube portion of the frame. The movable section hasa chain guide with a pair of cage plates for contacting and moving achain between the front sprockets.

The movable section is movable relative to the fixed member by pulling ashift control cable. In particular, the movable section and fixed memberusually are interconnected through pivotal links. The control cable isconnected to one of the pivotal links to apply a torque thereto, therebycausing the links to move the movable section. The control cable isfixedly coupled to the link in such a position that an operating forceis applied to the control cable. This force on the cable is convertedinto a link swinging torque. Depending on the arrangement and locationsof the cable guides, the cable attachment member of the front derailleurmay need to be configured differently for different types of frames.

In any case, the linkage assembly of a typical front derailleur isusually constructed of several small plates coupled together. The platesare typically narrow plates located close together to move the chainguide between the various positions. One problem with the typical frontderailleur is that the plates experience a variety of forces from thecontrol element (wire), links and chain (resistance). These forces cancause flexing of the links and the chain guide. Thus, smooth shiftingcan be adversely affected. Additionally, the typical front derailleurcan become clogged with mud, dirt or debris. If the derailleur becomesclogged with debris, smooth shifting can again be adversely affected.These prior art derailleurs are often relatively heavy. Moreover, theseprior art derailleurs can be complicated and expensive to manufactureand assemble.

In view of the above, there exists a need for a front derailleur for abicycle, which overcomes the above mentioned problems in the prior art.This invention addresses this need in the prior art as well as otherneeds, which will become apparent to those skilled in the art from thisdisclosure.

SUMMARY OF THE INVENTION

One object of the present invention is to provide front derailleur,which provides smooth, reliable shifting of the chain guide even whenriding in extreme riding conditions such as through mud, rain, or dirt.

Another object of the present invention is to provide front derailleurthat supports the chain guide by a wide link to prevent flexing of thechain guide during shifting.

Another object of the present invention is to provide front derailleur,which is relatively simple and inexpensive to manufacture and assemble.

The foregoing objects can basically be attained by providing a frontderailleur comprising a fixed member, a chain guide and a linkageassembly. The fixed member has a mounting portion configured to becoupled to a frame portion of the bicycle, a first mounting flange and asecond mounting flange axially spaced from the first mounting flange.The chain guide has a chain receiving slot to shift a chain of thebicycle in a transverse direction. The linkage assembly is coupledbetween the chain guide and the fixed member to move the chain guidebetween a retracted position and an extended position. The linkageassembly includes a first link, a second link and a third link. Thefirst link is pivotally coupled to the fixed member at a first pivotpoint for rotation about a first pivot axis. The second link ispivotally coupled to the first and second mounting flanges for rotationabout a second pivot axis passing through the first and second mountingflanges that is substantially parallel to the first pivot axis. Thethird link is coupled to the chain guide and movably coupled to thefirst and second links to form a four-bar linkage together with thefixed member. The first and second mounting flanges having differentaxial widths, as measured along the second pivot axis.

The foregoing objects can also basically be attained by providing afront derailleur comprising a fixed member, a chain guide and a linkageassembly. The fixed member has a mounting portion configured to becoupled to a frame portion of the bicycle, a first mounting flange and asecond mounting flange axially spaced from the first mounting flange.The chain guide has a chain receiving slot to shift a chain of thebicycle in a transverse direction. The linkage assembly is coupledbetween the chain guide and the fixed member to move the chain guidebetween a retracted position and an extended position. The linkageassembly includes a first link, a second link and a third link. Thefirst link is pivotally coupled to the fixed member at a first pivotpoint for rotation about a first pivot axis. The second link ispivotally coupled to the first and second mounting flanges for rotationabout a second pivot axis passing through the first and second mountingflanges that is substantially parallel to the first pivot axis. Thesecond link has a longitudinal dimension measured along the second pivotaxis that is at least about 45.0 millimeters in length. The third linkis coupled to the chain guide and movably coupled to the first andsecond links to form a four-bar linkage together with the fixed member.

These and other objects, features, aspects and advantages of the presentinvention will become apparent to those skilled in the art from thefollowing detailed description, which, taken in conjunction with theannexed drawings, discloses a preferred embodiment of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the attached drawings which form a part of thisoriginal disclosure:

FIG. 1 is a side elevational view of a conventional bicycle with a frontderailleur coupled thereto in accordance with a preferred embodiment ofthe present invention;

FIG. 2 is an enlarged, reverse perspective view of a portion of theframe of the bicycle illustrated in FIG. 1 with the front derailleurcoupled thereto, with a control element (wire) extending upwardly fromthe front derailleur along the portion of the frame;

FIG. 3 is an enlarged, reverse perspective view of a portion of theframe of the bicycle illustrated in FIG. 1 with the front derailleurcoupled thereto, with a control element (wire) extending downwardly fromthe front derailleur along the portion of the frame;

FIG. 4 is a top plan view of the front derailleur illustrated in FIGS.1–3, with the front derailleur removed from the bicycle frame;

FIG. 5 is an outside elevational view of the front derailleurillustrated in FIG. 4;

FIG. 6( a) is an enlarged, rear end elevational view of the frontderailleur (with the chain guide in the retracted position) illustratedin FIGS. 4 and 5, with the portion of the bicycle frame shown in phantomlines and the four bar linkage diagrammatically illustrated in phantomlines;

FIG. 6( b) is an enlarged, rear end elevational view of the frontderailleur (with the chain guide in the extended position) illustratedin FIGS. 4 and 5, with the portion of the bicycle frame shown in phantomlines and the four bar linkage diagrammatically illustrated in phantomlines;

FIG. 7 is a partial, exploded top plan view of the front derailleurillustrated in FIGS. 1–6;

FIG. 8 is an enlarged, top plan view of the first clamping member (i.e.part of the fixed member) of the front derailleur illustrated in FIGS.1–7;

FIG. 9 is a rear end elevational view of the first clamping member(fourth link) illustrated in FIG. 8;

FIG. 10 is a front end elevational view of the first clamping memberillustrated in FIGS. 8 and 9;

FIG. 11 is a bottom plan view of the first clamping member illustratedin FIGS. 8–10;

FIG. 12 is an enlarged, top plan view of the support link (second link)of the front derailleur illustrated in FIGS. 1–7;

FIG. 13 is an inside side elevational view of the support linkillustrated in FIG. 12;

FIG. 14 is a front end elevational view of the support link illustratedin FIGS. 12 and 13;

FIG. 15 is a rear end elevational view of the support link illustratedin FIGS. 12–14;

FIG. 16 is an enlarged, rear end elevational view of the cableattachment link (first link) of the front derailleur illustrated inFIGS. 1–7;

FIG. 17 is an outside elevational view of the cable attachment linkillustrated in FIG. 16;

FIG. 18 is a front end elevational view of the cable attachment linkillustrated in FIGS. 16 and 17;

FIG. 19 is an inside elevational view of the cable attachment linkillustrated in FIGS. 16–18, as viewed along section line 19—19 of FIG.18;

FIG. 20 is an enlarged, top plan view of the inner guide plate (thirdlink) of the chain guide of the front derailleur illustrated in FIGS.1–7;

FIG. 21 is an outside elevational view of the inner guide plateillustrated in FIG. 20;

FIG. 22 is a rear end elevational view of the inner guide plateillustrated in FIGS. 20 and 21; and

FIG. 23 is a front end elevational view of the inner guide plateillustrated in FIGS. 20–22.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring initially to FIGS. 1–3, a bicycle 10 is illustrated with afront derailleur 12 fixedly coupled to its seat post portion 14 of itsframe, in accordance with a preferred embodiment of the presentinvention. The front derailleur 12 is operated by a shifting unit 16 viaa shift cable 18 to move a chain 19 between front sprockets or chainrings 20.

Referring to FIGS. 1–7, the front derailleur 12 of the present inventionbasically includes a fixed member 22 (with an axially extending linksupporting projection or flange), a cable attachment link 24, a widesupport link 26 and a chain guide 28. The fixed member 22 is preferablya tubular clamping member or mechanism. The chain guide 28 is movablysupported on the fixed member 22 by the cable attachment link 24 and thesupport link 26 to move between the various shift positions thatcorrespond to the front sprockets 20. The cable attachment link 24rotates about an axis A adjacent the center axis of the seat postportion 14 (coinciding with a center axis X of a curved surface of thefixed member 22 in the illustrated embodiment). The center axis X liessubstantially in a longitudinal center plane P of the seat post portion14 (in the illustrated embodiment). Portions of the fixed member 22, thecable attachment link 24, the support link 26 and the chain guide 28form a linkage assembly 30 that is relatively wide. The location of therotation axis A of the cable attachment link 24 and the wideconfiguration of the linkage assembly 30 aid in providing smooth,reliable shifting of the chain 19 between the sprockets 20, as discussedbelow in more detail.

The front derailleur 12 is designed to accommodate a wide variety ofbicycles. In particular, front derailleur 12 can be used with the shiftcable 18 coming from above the front derailleur 12 as seen in FIG. 2, orwith the shift cable 18 coming from below the front derailleur as seenin FIG. 3. In other words, the cable 18 can be coupled to the cableattachment link 24 of the front derailleur 12 such that its inner wireis either pulled upwardly or downwardly from front derailleur 12 by theshifting unit 16.

Bicycles and their various components are well known in the art, andthus, bicycle 10 and its various components will not be discussed orillustrated in detail herein except for the components that relate tothe present invention. In other words, only front derailleur 12 and thecomponents that relate thereto will be discussed and/or illustrated indetail herein.

As used herein, the terms “forward, rearward, upward, above, downward,below and transverse” refer to those directions of a bicycle in itsnormal riding position, to which the front derailleur 12 is attached.Accordingly, these terms, as utilized to describe the front derailleur12 in the claims, should be interpreted relative to the bicycle 10 inits normal riding position.

While the front derailleur 12 is illustrated as being fixedly coupled tothe seat post portion 14 of the bicycle frame, it will be apparent tothose skilled in the art from this disclosure that front derailleur 12can be coupled to other parts of the bicycle such as the bottom bracketas needed and/or desired. In any event, the fixed portion 22 preferablyincludes a curved surface configured to contact the seat post portion14, as discussed in more detail below.

The linkage assembly 30 is preferably a four bar linkage assembly thatis defined by four pivot axes A, B, C and D as best seen in FIGS. 6( a)and 6(b). A portion of the cable attachment link 24 defines a first linkbetween the pivot axes A and B. A portion of the support link 26 definesa second link between the pivot axes C and D. A portion of the chainguide 28 defines a third link between the pivot axes B and D. A portionof the fixed member 22 defines a fourth link between the pivot axes Aand C. Thus, the front derailleur 12 basically includes the fixed ortubular clamping member 22, the chain guide 28 and the linkage assembly30 coupled between the fixed member 22 and the chain guide 28 to formthe four-bar linkage.

The cable attachment link 24 is pivotally supported on a pivot pin 23that is fixedly coupled to the fixed member 22. A pair of pivot pins 25a and 25 b that are located on the pivot axis C pivotally support oneend of the support link 26 on the fixed member 22. The other end of thesupport link 26 pivotally supports the chain guide 28 by a pair of pivotpins 27 a and 27 b that are located on the pivot axis D. A pivot pin 29located on the pivot axis B is pivotally coupled to the cable attachmentlink 24 and pivotally supports the chain guide 28. Thus, the chain guide28 is movably coupled to the cable attachment link 24 and the supportlink 26 to move between a retracted (low gear) position and an extended(high gear) position, as seen in FIGS. 6( a) and 6(b).

As best seen in FIGS. 2, 3, 6(a) and 6(b), the fixed member 22 ispreferably located beneath the chain guide 28 (at least below the topportion of the chain guide 28 coupled to the cable attachment link 24and the support link 26). The linkage assembly 30 is preferably designedsuch that a biasing member (torsion spring) 31 normally biases the chainguide 28 in a transverse direction towards the frame of bicycle 10. Inother words, when the chain guide 28 is closest to the frame of bicycle10, the chain guide 28 holds the chain 19 over the sprocket 20 that isclosest to the seat post portion 14.

When the linkage assembly 30 holds chain guide 28 in its extendedposition, the chain guide 28 is located over the outermost sprocket 20,i.e., the furthest sprocket 20 from the seat post portion 14. Thesemovements of the chain guide 28 and the linkage assembly 30 arecontrolled by the shifting unit 16. Specifically, when the ridersqueezes the lever of the shifting unit 16, this pulls the shift cable18 to move the chain guide 28 between its retracted position and itsextended position via the linkage assembly 30. The shifting unit 16 isconventional and can be any of a variety of types of shifting units.Therefore, the precise structure of the shifting unit 16 will not bediscussed or illustrated in detail herein.

As seen in FIGS. 2–11, the fixed member 22 is preferably clampeddirectly to the seat post portion 14. The fixed member 22 basicallyincludes a first clamping portion 32, a second C-shaped clamping portion34, a pivot pin 36 and a fastener 38, as best seen in FIG. 4. First andsecond clamping portions 32 and 34 are constructed of a rigid materialto secure the front derailleur 12 to the seat post portion 14 of thebicycle 10. Preferably, clamping portions 32 and 34 are constructed ofmetal. Of course, clamping portions 32 and 34 could be constructed ofother materials such as a hard rigid plastic material. Moreover, each ofthe clamping portions 32 and 34 could be constructed of a differentmaterial. In the illustrated embodiment, the clamping portions 32 and 34are constructed by utilizing manufacturing techniques such as castingand/or machining. Of course, the clamping portions 32 and 34 can also beconstructed of sheet metal that is bent to the desired shape.

First ends of clamping portions 32 and 34 are pivotally coupled togetherby the pivot pin 36, which extends in a substantially vertical directionrelative to the bicycle 10 in a conventional manner. The other ends ofclamping portions 32 and 34 are releasably connected together via thefastener 38. The fastener 38 is preferably a screw or bolt that isinserted through an unthreaded hole of the clamping member 34 andthreaded into a threaded hole of first clamping portion 32. Of course,the fastener 38 can be utilized in conjunction with a nut, or the like.The structure of the clamping member 34 is relatively conventional.Accordingly, the clamping member 34 will not be discussed and/orillustrated in detail herein.

Of course, it will be apparent to those skilled in the art from thisdisclosure that front derailleur 12 can be coupled to other parts of thebicycle such as the bottom bracket as needed and/or desired. Moreover,it will be apparent to those skilled in the art from this disclosurethat other structures could be utilized to couple the front derailleur12 to the bicycle 10 without departing from the scope of the presentinvention. In any event, the fixed member 22 preferably includes amounting surface (a curved mounting surface in the illustratedembodiment) configured to contact the seat post portion 14, and preventlongitudinal movement of the front derailleur 12. For example, thesecond clamping portion 34 could be omitted, and the first clampingportion 32 could be coupled to a bottom bracket mounting portion. Thus,the term “fixed member” as used herein means any suitable structurenon-movably coupled to the seat post portion 14 and/or the bicycle 10.

Referring to FIGS. 7–11, the first clamping portion 32 includes portionsof the linkage assembly 30. In other words, portions of the linkageassembly 30 are integrally formed with the first clamping portion 32.Specifically, the first clamping portion 32 has a pair (first andsecond) of mounting flanges 40 and 42 that extend outwardly from aC-shaped mounting portion 44 (with a curved mounting surface 45). Themounting portion 44 is pivotally coupled to the second clamping portion34 via the pivot pin 36 to clamp the fixed member 22 to the seat postportion 14 via the fastener 38.

The mounting flanges 40 and 42 have pivot holes 41 and 43 formedtherein, respectively. The pair of pivot pins 25 a and 25 b are receivedin the pivot holes 41 and 43, respectively for mounting the support link26 of the linkage assembly 30 thereto. The first clamping portion 32also has a threaded pivot hole 46 for fixedly receiving the pivot pin 23therein. A cutout 47 is preferably provided to reduce weight. The cableattachment link 24 is pivotally mounted on the pivot pin 23 for rotationabout the (first) pivot axis A. The pivot axis A is preferably spaced adistance M less than about 5.0 millimeters from the center plane P ofthe seat post portion 14 (frame portion), measured perpendicular to the(first) pivot axis A, as discussed below in more detail. An additionalmounting hole 48 is formed in the first clamping portion 32. A stop pin49 is fixedly coupled to the first clamping portion 32 within themounting hole 48 to engage a portion of the biasing member (torsionspring) 31.

The pivot holes 41 and 43 are preferably aligned with each other andhave the (second) pivot axis B passing through their centers. Thus, thesupport link 26 is pivotally coupled to the fixed member 22 for rotationabout the pivot axis B. The pivot axis B is preferably substantiallyparallel to the pivot axis A. The (first and second) mounting flanges 40and 42 have different axial widths, as measured relative to the pivotaxis B. Specifically, the (first) mounting flange 40 has an axial widthL₁, while the (second) mounting flange 42 has an axial width L₂ smallerthan the axial width L₁. More specifically, the axial width L₁ ispreferably about 24.8 millimeters, while the axial width L₂ ispreferably about 3.6 millimeters. In any event, the axial width L₁ ispreferably at least about five times larger the axial width L₂, and theaxial width L₁ is preferably at least about 21.0 millimeters.

The (first) mounting flange 40 extends axially along the pivot axis Baway from the mounting portion 44 of the fixed member 22 to form a firstlink receiving recess R between the mounting flange 40 and the mountingportion 44. The first link receiving recess R is configured such thatcable attachment link 24 is at least partially disposed therein. Thus,the first link receiving recess R is preferably at least partiallyaligned with the mounting flange 42 in a direction perpendicular to thefirst and second pivot axes A and B. Therefore, when the frontderailleur 12 is assembled, the cable attachment link 24 is preferablyat least partially aligned with the (first) mounting flange 40.

The curved mounting surface 45 of the mounting portion 44 preferably hasa radius of curvature Y of about 34.9 millimeters formed about centeraxis X. Thus, if the seat post portion 14 has substantially the samecurvature as mounting surface 45, the center plane P of the seat postportion 14 has the center axis X lying therein (as in the illustratedembodiment). In such an arrangement, the pivot axis A is preferablyspaced a distance M of about 2.0 millimeters from the center plane P anda distance N of about 2.0 millimeters from the center axis X, asmeasured in a direction perpendicular to the pivot axis A.

Of course, it will be apparent to those skilled in the art from thisdisclosure that the mounting surface 45 could have a larger or smallercurvature if needed and/or desired. It will also be apparent to thoseskilled in the art from this disclosure that the mounting surface 45could have other shapes or configurations as needed and/or desireddepending on the structure of the frame of the bicycle 10. Finally itwill be apparent to those skilled in the art from this disclosure thatthe pivot axis A could be closer to or farther from the center axis X ofthe mounting surface 45 (i.e. N could be greater or less than 2.0millimeters), depending on the configuration of the seat post portion14.

In any event, the mounting surface 45 is preferably sized and configuredsuch that the center plane P (coinciding with the center of curvature Xin the illustrated embodiment) is spaced a distance M less than about5.0 millimeters from the pivot axis A. Moreover, the pivot axis A isalso preferably located relative to center axis X such that pivot axis Ais spaced less than about 5.0 millimeters from the center plane P. Inother words, in the illustrated embodiment, distances M and N are equalto each other and about 2.0 millimeters. However, it will be apparent tothose skilled in the art from this disclosure that distances M and Ncould be different if needed and/or desired. However, the distance M ispreferably less than about 5.0 millimeters.

In the illustrated embodiment, a distance L₃ measured betweencorresponding axially facing end surfaces of the mounting flanges 40 and42 is preferably about 49.2 millimeters. In any event, distance L₃ ispreferably at least about 45.0 millimeters. The corresponding axiallyfacing surfaces (spaced L₃ from each other) are configured to mountportions of the support link 26 adjacent thereto. Thus, a wide supportstructure for the support link 26 is provided.

Referring to FIGS. 2–7 and 12–15, the support link 26 basically includesa pair (first and second) of link plates 50 and 52 with a supportportion 54 extending between the link plates. The support link 26 ispreferably constructed of a hard rigid material. For example, thesupport link is preferably constructed of metal such as a rigid sheetmetal that is bent to the desired shape. When the front derailleur isassembled, the link plates 50 and 52 are substantially vertical plates.The link plate 50 has a first pivot portion 51 a and a second pivotportion 51 b, while the link plate 52 has a first pivot portion 53 a anda second pivot portion 53 b.

The first pivot portions 51 a and 53 a are pivotally coupled to themounting flanges 40 and 42 via the pivot pins 25 a and 25 b,respectively. Specifically, the first pivot portions 51 a and 53 a haveholes 55 a and 57 a formed therein for receiving the pivot pins 25 a and25 b, respectively. Thus, the support link 26 is pivotally coupled tothe first clamping member 32 (fixed member 22). The second pivotportions 51 b and 53 b have holes 55 b and 57 b formed therein forreceiving the pivot pins 27 a and 27 b, respectively, to pivotallysupport the chain guide 28 via the pivot pins 27 a and 27 b, asdiscussed below.

The first pivot portions 51 a and 53 a have corresponding axially facingsurfaces spaced a distance L₃ apart from each other. The length L₃ ispreferably about 49.2 millimeters such that a relatively wide supportfor the chain guide 28 is provided. In any event, the longitudinaldimension (i.e. L₃) of the support link is preferably at least about45.0 millimeters as measured along pivot axis B. The correspondingaxially facing surfaces of first pivot portions 51 a and 53 a arearranged adjacent the mounting flanges 40 and 42, respectively when thefront derailleur 12 is assembled. The first pivot portion 51 a ispreferably offset from the second pivot portion 51 b. The supportportion also has a bulged section 56 (i.e. a non-constant cross-section)as seen in FIGS. 12–15 to increase the strength and rigidity of thesupport link 26.

The second pivot portion 51 b is provided with a fan-shaped member 58that engages adjustment screws 62 and 63 for limiting movement of chainguide 28 between its retracted position and its extended position, asseen in FIGS. 2–4. More specifically, the fan member 58 is provided witha high stopping surface 59 and a low stopping surface 60 as best seen inFIGS. 14 and 15. High stopping surface 59 is designed to engage the freeend of high adjustment screw 62, while the low stopping surface 60 ispositioned to engage the low adjustment screw 63. Since this is arelatively conventional adjustment mechanism that is well known in theprior art, this adjustment mechanism will not be discussed orillustrated in detail herein.

Referring to FIGS. 2–7 and 16–19, the cable attachment link 24 basicallyincludes a mounting portion 64, a link portion 66 and a cable attachmentportion 68. The cable attachment link 24 is preferably constructed of ahard, rigid material. For example, the cable attachment link ispreferably constructed by utilizing manufacturing techniques such ascasting and/or machining. The mounting portion 64 has a pivot hole 65,while the link portion 66 has a pivot hole 67. The pivot hole 67 definesa link attachment portion surrounding the pivot hole 67. The cableattachment portion 68 has a threaded bore 69 for coupling a wire clamp70 thereto via a fastener 71 (FIGS. 6( a) and 6(b)). The fastener 71 ispreferably a screw or bolt, which fixedly secures the wire clamp 70thereto.

The wire clamp 70 is preferably a substantially L-shaped plate memberthat fixedly frictionally secures the inner wire of the cable 18 to thecable attachment link 24 when the bolt 71 is tightened against the wireclamp 70. The cable attachment link 24 also preferably has a groove 72arranged around a portion of it's periphery to guide the inner wire ofthe cable 18 from wire clamp 70, such that the inner wire of cable 18extends downwardly from the front derailleur 12 (FIG. 3). Alternatively,the inner wire of the cable 18 is not positioned in the groove 72, suchthat the inner wire of the cable 18 extends upwardly along the seat postportion 14 (FIG. 2).

The mounting portion 64 is pivotally coupled on the pivot pin 23 forrotation about the pivot axis A. The link portion 66 pivotally supportsthe chain guide via the pivot pin 29. When the inner wire of the cable18 is pulled via the shifting unit 16, the cable attachment link rotatesabout the pivot axis A. Thus, the link portion 66 also rotates about thepivot axis A, which then moves the chain guide 28 via the pivot pin 29.The mounting portion includes an annular recess 74 with a notch 75extending therefrom as seen in FIG. 18. The notch 75 is designed toengage an end of the biasing member 31 as discussed below.

As best seen in FIGS. 2–7 and 20–23, the chain guide 28 is preferablyconstructed of a hard rigid material. For example, the chain guide 28 ispreferably constructed of metal such as a rigid sheet metal that is bentto the desired shape. The chain guide 28 has a chain receiving slot 80formed by a pair of vertical shift plates 81 and 82 that are adapted toengage the chain 19 for moving the chain 19 in a direction transverse tothe bicycle 10. The shift plates 81 and 82 (i.e. inner and outer shiftplates) are connected together by plates 83 and 84. The plate 83 has oneend that is integrally formed with the shift plate 82 and another endthat is detachably coupled to the shift plate 81 via screws 85. Theshift plate 84 also has one end integrally formed with the shift plate82 and another end that is detachably coupled to the shift plate 81 viaa single screw 85.

The chain guide 28 also has a pair of mounting flanges 86 and 87extending in a substantially vertical direction from the shift plate 81for coupling the linkage assembly 30 thereto. A portion of the mountingflange 86 forms one of the links (third link) of the linkage assembly30. More specifically, the mounting flange 86 has a substantiallyhorizontal section 88 and a substantially vertical section 89. Thevertical section 89 preferably has a pair of substantially flat verticalsurfaces. The horizontal section 88 has a pair of threaded holes 90 and91 for receiving the adjustment screws 62 and 63 therein, respectively.The adjustment screw 62 is a high position adjustment screw, while theadjustment screw 63 is a low position adjustment screw. The adjustmentscrews 62 and 63 selectively engage a portion of linkage assembly 30(the support link 26) for controlling the range of movement of the chainguide 28 in a conventional manner. In other words, by individuallyadjusting the axial extension of the adjustment screws 62 and 63relative to the horizontal section 88, the retracted (low gear) positionand the extended (high gear) position of the chain guide 28 are adjustedindependently of each other.

The vertical section 89 of the mounting flange 86 has a pair of pivotholes 92 and 93 a for pivotally mounting parts of the linkage assembly30 thereto. The mounting flange 87 also has a pivot hole 93 b that isaligned with the pivot hole 93 a of the vertical section 89 forpivotally coupling parts of the linkage assembly 30 therebetween.Specifically, the pivot hole 92 pivotally receives the pivot pin 29(couple to the cable attachment link 24), while pivot holes 93 a and 93b pivotally receive the pivot pins 27 a and 27 b, respectively. Thus,the chain guide 28 is movably coupled to the cable attachment link 24and the support link 26 via the pivot pin 29 and the pivot pins 27 a and27 b, respectively.

A plurality of snap-on retaining washers 94 are utilized on the pivotpins 23, 25 a, 25 b, 27 a, 27 b and 29, as seen in FIGS. 2, 3 and 7.More specifically, each of the pivot pins 23, 25 a, 25 b, 27 a, 27 b and29 has a groove for receiving retaining washers 94. Preferably, theseretaining washers 94 are E-shaped retaining clips that are snapped intoretaining grooves of the pivot pins. Optionally, the pivot pins 23, 25a, 25 b, 27 a, 27 b and 29 can be utilized with bushings (not shown)mounted in their respective pivot holes. Of course, it will be apparentto those skilled in the art from this disclosure that any suitable pivotpins could be used in conjunction with the present invention. Forexample, rivet-type pivot pins could be utilized.

The biasing member 31 is preferably a torsion spring having its coiledportion positioned around pivot pin 23. The biasing member 31 has afirst end arranged in the notch 75 (FIGS. 7 and 18) of the cableattachment link 24, and a second end engaging the stop pin 49 of thefixed member 22 (FIGS. 4 and 7) for normally biasing the chain guide 28from its extended position to its retracted position. In other words,the biasing member or torsion spring 31 is normally placed under tensionto urge the cable guide 28 from its extended position to its retractedposition. Of course, movement of chain guide 28 is controlled byshifting unit 16 moving cable 18 in a relatively conventional manner.

The terms of degree such as “substantially”, “about” and “approximately”as used herein mean a reasonable amount of deviation of the modifiedterm such that the end result is not significantly changed. These ternsshould be construed as including a deviation of at least±5% of themodified term if this deviation would not negate the meaning of the wordit modifies.

While only selected embodiments have been chosen to illustrate thepresent invention, it will be apparent to those skilled in the art fromthis disclosure that various changes and modifications can be madeherein without departing from the scope of the invention as defined inthe appended claims. Furthermore, the foregoing description of theembodiments according to the present invention are provided forillustration only, and not for the purpose of limiting the invention asdefined by the appended claims and their equivalents.

1. A front derailleur for a bicycle comprising: a fixed member having amounting portion configured to be coupled to a frame portion of thebicycle, said fixed member including a first mounting flange and asecond mounting flange axially spaced from said first mounting flange; achain guide having a chain receiving slot to shift a chain of thebicycle in a transverse direction; and a linkage assembly coupledbetween said chain guide and said fixed member to move said chain guidebetween a retracted position and an extended position; said linkageassembly including a first link pivotally coupled to said fixed memberat a first pivot point for rotation about a first pivot axis, a secondlink pivotally coupled to said first and second mounting flanges forrotation about a second pivot axis passing through said first and secondmounting flanges that is substantially parallel to said first pivotaxis, and a third link coupled to said chain guide and movably coupledto said first and second links to form a four-bar linkage together withsaid fixed member, said first and second mounting flanges havingdifferent axial widths, as measured along said second pivot axis, saidaxial width of said first mounting flange being at least about fivetimes thicker than said axial width of said second mounting flange withsaid first mounting flange being at least partially aligned with saidfirst link in a direction perpendicular to said first and second pivotaxes.
 2. A front derailleur for a bicycle comprising: a fixed memberhaving a mounting portion configured to be coupled to a frame portion ofthe bicycle, said fixed member including a first mounting flange and asecond mounting flange axially spaced from said first mounting flange; achain guide having a chain receiving slot to shift a chain of thebicycle in a transverse direction; and a linkage assembly coupledbetween said chain guide and said fixed member to move said chain guidebetween a retracted position and an extended position; said linkageassembly including a first link pivotally coupled to said fixed memberat a first pivot point for rotation about a first pivot axis, a secondlink pivotally coupled to said first and second mounting flanges forrotation about a second pivot axis passing through said first and secondmounting flanges that is substantially parallel to said first pivotaxis, said second link having a longitudinal dimension measured alongsaid second pivot axis that is at least about 45.0 millimeters inlength, and a third link coupled to said chain guide and movably coupledto said first and second links to form a four-bar linkage together withsaid fixed member, said first mounting flange extending axially alongsaid second pivot axis away from said mounting portion of said fixedmember to form a first link receiving recess between said first mountingflange and said mounting portion, said first link receiving recess beingconfigured such that a majority of said first link is disposed therein.3. The front derailleur according to claim 2, wherein said fixed memberis configured with said first pivot axis being spaced less than about5.0 millimeters from a center plane of the frame portion, measuredperpendicular to said first pivot axis.
 4. The front derailleuraccording to claim 2, wherein said first and second mounting flangeshave different axial widths, as measured along said second pivot axis.5. The front derailleur according to claim 4, wherein said axial widthof said first mounting flange is at least about five times thicker thansaid axial width of said second mounting flange with said first mountingflange being at least partially aligned with said first link in adirection perpendicular to said first and second pivot axes.
 6. Thefront derailleur according to claim 5, wherein said first mountingflange is at least about 21 millimeters thick, as measured along saidsecond pivot axis.
 7. The front derailleur according to claim 5, whereinsaid first link has a cable attachment point adapted to fixedly couple acontrol element thereto.
 8. The front derailleur according to claim 7,wherein said linkage assembly includes a biasing member normally urgingsaid chain guide to one of said retracted and extended positions.
 9. Thefront derailleur according to claim 8, wherein said fixed member is atubular clamping member.
 10. A front derailleur for a bicyclecomprising: a fixed member having a mounting portion configured to becoupled to a frame portion of the bicycle, said fixed member including afirst mounting flange and a second mounting flange axially spaced fromsaid first mounting flange; a chain guide having a chain receiving slotto shift a chain of the bicycle in a transverse direction; and a linkageassembly coupled between said chain guide and said fixed member to movesaid chain guide between a retracted position and an extended position;said linkage assembly including a first link pivotally coupled to saidfixed member at a first pivot point for rotation about a first pivotaxis, a second link pivotally coupled to said first and second mountingflanges for rotation about a second pivot axis passing through saidfirst and second mounting flanges that is substantially parallel to saidfirst pivot axis, said second link having a longitudinal dimensionmeasured along said second pivot axis that is at least about 45.0millimeters in length, and a third link coupled to said chain guide andmovably coupled to said first and second links to form a four-barlinkage together with said fixed member, said first mounting flangeextending axially along said second pivot axis away from said mountingportion of said fixed member to form a first link receiving recessbetween said first mounting flange and said mounting portion of saidfixed member such that said first link is at least partially disposed insaid first link receiving recess to be at least partially aligned withsaid first mounting flange in a direction perpendicular to said firstand second pivot axes.
 11. The front derailleur according to claim 10,wherein said first link includes a link attachment portion that isaxially disposed between said third link and said fixed member, relativeto said first pivot axis.